Biomagnetism measurement system and method for sensing biomagnetic signals

A biomagnetic field sensor for detecting magnetic fields from the human body comprises: a tunnelling magnetoresistive (TMR) sensor unit 104 to measure a biological magnetic field; a gradiometer unit 108 to measure a background noise magnetic field; a shielding layer 106 between the TMR sensor and the gradiometer; an active noise cancellation unit 111 to remove the background noise from the biomagnetic signal; analogue read out circuitry 110; and an analogue to digital converter (ADC) to generate a digital output. The gradiometer may be a triaxial gradiometer and may also be based on TMR. The sensors of TMR unit 104 may be in a Wheatstone bridge arrangement. There may be a plurality of sensor units designed to contact the skin. Wireless communication may transmit the measured biomagnetic field data to a remote unit. The sensors may be worn on an elastic strap (figure 3). The sensor may be used without a shielded room due to the cancellation of magnetic noise fields.